This invention relates to a retractable writing implement, such as a fountain pen, a soft tip pen, or a ball-point pen, and is particularly applicable to such a pen which uses a volatile ink supply.
In general, when a writing implement is not being used a cap is put over its tip to prevent it from becoming dried out and/or for the protection of the tip and the clothing of the user. With a pen which uses a volatile ink supply, capping is particularly essential to prevent the evaporation of the ink supply.
To use a capped pen the cap must first be removed, which is a bothersome two hand operation. In some pens the removed cap may be placed over the rear end of the pen body, but this is also rather troublesome, and the cap frequently works loose and becomes lost or mislaid.
In order to eliminate the above-described difficulties accompanying conventional capped writing implements, a variety of retractable pen designs have been proposed. These are generally intricate and costly to construct, however, and because of their complex design they are subject to frequent malfunction, such as jamming, and their repair is very difficult. Further, conventional retractable pens are often fatally disadvantageous in that the writing section is not satisfactorily sealed when the pen is not in use.
As examples of various prior art retractable pen constructions, see Japanese Patent Publications Nos. 45/16885, 45/22650, 50/13138, 50/9023, and 51/94322.